What is roman numeral MDCCCXLIL?

Answer 1

It is, unfortunately, not a number. The skew in your Roman numeral is the last L. L = 50. An L can't be used twice in a Roman numeral in this configuration.

MDCCCXLII on the other hand is: 1842.

MDCCCXIII is 1813.

M = 1,000

D = 500

C = 100

L = 50 (X=10; XL = 50 minus 10 which is 40)

Any digits that come after that have to be less than 10 and cannot include numbers like X, L, C, D, or M.

Answer 2

They are an invalid arrangement of Roman numerals.